for low light events shooting with such a wide lens and wide open, what you do is you prefocus to a certain distance, say at 2.6 meters ( 8.5 feet, whatever) this gives at 14mm and F1.8 a very generous depth of field being: 1.5 meters to 8.8 meters. Plenty enough! Set the lens to MF. AF accuracy aside, it takes longer for AF to kick in when it is really dark. that is how we shoot the dance floor. I hope it makes sense.
in addition, such a wide lenses are always AF inaccurate due to AF point covers larger area of the setting. Canon AF point size is roughly 2-3 percent of the viewfinder last time I checked. 14mm lens FOV is approx. 114 degrees diagonally. so that is a massive 2-3 degree. what the lens will focus on remains to be seen. Spot-AF should be more appropriate in this case to use but known to struggle in low light and in AI Servo mode.